1. Field of the Invention
The present invention relates to oil drilling equipment to be installed in ice covered sea areas and, more particularly, to a working platform for oil drilling operations, which is suitable for comparatively shallow ice covered sea areas.
2. Description of the Prior Art
In an ice covered sea area, for example, the Arctic Ocean, the fast ice is moved by a small distance, or around 20 m at most during the winter months.
In order to conduct an oil drilling operation in such an ice covered sea area of a small depth (of not more than 20 m), a method of installing oil drilling equipment on an artificial island has heretofore been employed, which artificial island is formed with sand or gravel accumulated in the sea area, or the fast ice in the sea area.
However, it is necessary that such an artificial island be formed to large dimensions so that it can stand floating ice running thereon and the pressure of large ice blocks surrounding the same. Such an artificial island can be formed only in a shallow sea area and requires 1-2 months to build. Moreover, it is difficult to remove an artificial island, if it is formed with sand or gravel, after oil drilling operations have been completed. Removing such an artificial island poses problems of environmental pollution.
In order to conduct oil drilling operations on an artificial island, it is also necessary to transport oil drilling equipment and various kinds of materials from a coastal area near the same. This often results in a delay in starting the object operations.
As may be clearly understood from the above, it takes a long period of time to build an artifical island. In addition, the building of such an artificial island incurs a great deal of expense.